/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */

package org.apache.iotdb.confignode.procedure;

import org.apache.iotdb.confignode.procedure.store.IProcedureStore;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.util.Iterator;
import java.util.Map;
import java.util.concurrent.TimeUnit;

/**
 * Internal cleaner that removes the completed procedure results after a TTL.
 */
public class CompletedProcedureRecycler<Env> extends InternalProcedure<Env> {
    private static final Logger LOG = LoggerFactory.getLogger(CompletedProcedureRecycler.class);
    private static final int DEFAULT_BATCH_SIZE = 32;
    private long evictTTL;
    private final Map<Long, CompletedProcedureContainer<Env>> completed;
    private final IProcedureStore store;

    public CompletedProcedureRecycler(
            IProcedureStore store,
            Map<Long, CompletedProcedureContainer<Env>> completedMap,
            long cleanTimeInterval,
            long evictTTL) {
        super(TimeUnit.SECONDS.toMillis(cleanTimeInterval));
        this.completed = completedMap;
        this.store = store;
        this.evictTTL = evictTTL;
    }

    @Override
    protected void periodicExecute(final Env env) {
        if (completed.isEmpty()) {
            if (LOG.isTraceEnabled()) {
                LOG.trace("No completed procedures to cleanup.");
            }
            return;
        }

        final long[] batchIds = new long[DEFAULT_BATCH_SIZE];
        int batchCount = 0;

        final long now = System.currentTimeMillis();
        final Iterator<Map.Entry<Long, CompletedProcedureContainer<Env>>> it =
                completed.entrySet().iterator();
        while (it.hasNext() && store.isRunning()) {
            final Map.Entry<Long, CompletedProcedureContainer<Env>> entry = it.next();
            final CompletedProcedureContainer<Env> retainer = entry.getValue();
            final Procedure<?> proc = retainer.getProcedure();
            if (retainer.isExpired(now, evictTTL)) {
                // Failed procedures aren't persisted in WAL.
                batchIds[batchCount++] = entry.getKey();
                if (batchCount == batchIds.length) {
                    store.delete(batchIds, 0, batchCount);
                    batchCount = 0;
                }
                it.remove();
                LOG.trace("Evict completed {}", proc);
            }
        }
        if (batchCount > 0) {
            store.delete(batchIds, 0, batchCount);
        }
    }
}
